Related papers: Elastic-to-plastic crossover below the peak effect…
We report on marked memory effects in the vortex system of twinned YBa2Cu3O7 single crystals observed in ac susceptibility measurements. We show that the vortex system can be trapped in different metastable states with variable degree of…
Two-dimensional(2D) vortex dynamics was studied in an YBa_2Cu_3O_7/ PrBa_2Cu_3O_7 superlattice by measuring the I-V characteristics. In the high current limit, 2D collective creep was observed with an activation energy characterized by…
We report on the degree of order of the vortex solid in YBa2Cu3O7 single crystals observed in ac susceptibility measurements. We show that when vortices are "shaken" by a temporarily symmetric ac field they are driven into an easy-to-move,…
We propose a phenomenological model that accounts for the history effects observed in ac susceptibility measurements in YBa2Cu3O7 single crystals [Phys. Rev. Lett. 84, 4200 (2000) and Phys. Rev. Lett. 86, 504 (2001)]. Central to the model…
The vortex lattice in a Type II superconductor provides a versatile model system to investigate the order-disorder transition in a periodic medium in the presence of random pinning. Here, using scanning tunnelling spectroscopy in a weakly…
We studied thermal and dynamic history effects in the vortex lattice (VL) near the order-disorder transition in clean NbSe$_2$ single crystals. Comparing the evolution of the effective vortex pinning and the bulk VL structure, we observed…
Transverse ac permeability measurements in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta }$ single crystals at low fields and temperatures in a vortex configuration free of external forces show that the decrease of the critical current as measured by…
The peak effect in weakly pinned superconductors is accompanied by metastable vortex states. Each metastable vortex configuration is characterized by a different critical current density J_c, which mainly depends on the past thermomagnetic…
Distinct discontinuities in the thermal expansion of the crystal lattice are observed at the melting-transition of the vortex lattice in a naturally untwinned reversible YBa2Cu3O7-d-single crystal using high-resolution dilatometry. This…
We have studied metastability effects pertaining to the peak effect (PE) in critical current density ($J_c$) via isofield scans in ac susceptibility measurements in a weakly pinned single crystal of Yb$_3$Rh$_4$Sn$_{13}$ ($T_c(0) \approx…
In type-II superconductors exposed to magnetic fields between upper and lower critical values, $H_{c1}$ and $H_{c2}$, penetrating magnetic flux forms a lattice of vortices whose motion can induce dissipation. Consequently, the magnetization…
We highlight interesting thermomagnetic history effects across the transition line between the (quasi) ordered and disordered vortex states in single crystal YBa$_2$Cu$_3$O$_{7-\delta}$, and argue that these features are indicative of the…
Local magnetic relaxation measurements in YBa$_2$Cu$_3$O$_{7-x}$ crystals show evidence for plastic vortex-creep associated with the motion of dislocations in the vortex lattice. This creep mechanism governs the vortex dynamics in a wide…
The dynamic transition between the ordered flow and the plastic flow is studied for a two-dimensional driven vortex lattice, in the presence of sharp and dense pinning centers, from numerical simulations. For this system, which does not…
A vortex lock-in transition was directly detected by torque magnetometry in an overdoped YBa2Cu3O7 single crystal of low anisotropy (\approx 7). The locked-in state was observed below the 3D to 2D crossover temperature Tcr = 76 K,…
In single crystals of 2H-NbSe2, we identify for the first time a crossover from weak collective to strong pinning regime in the vortex state which is not associated with the peak effect phenomenon. Instead, we find the crossover is…
Resistance in superconductors arises from the motion of vortices driven by flowing supercurrents or external electromagnetic fields and may be strongly affected by thermal or quantum fluctuations. The common expectation borne out in…
It is commonly accepted that the peak effect (PE) in the critical current density of type II superconductors is a consequence of an order-disorder transition in the vortex lattice (VL). Examination of vortex lattice configurations (VLCs) in…
Oscillatory dynamics and quasi-static Campbell regime of the vortex lattice (VL) in twinned YBa2Cu3O7 single crystals has been explored at low fields near the peak effect (PE) region by linear and non-linear ac susceptibility measurements.…
The peak effect in critical current density J_c is investigated by studying the flux dynamics in V_3Si using bulk magnetometry, small-angle neutron scattering, and transport measurements on clean single-crystal samples from the same ingot.…